Rates of displacement reactions

Table 4.9 Effect of Electron-Donating and -Withdrawing Substituents on the Rate of Displacement Reactions on Carbon and Sulfur...

The results for reaetion no. 8 in Table 5-15 indieate that nueleophilie reaetivities of anions obtained in the gas phase are essentially in the same order as in molten salts and in dipolar non-HBD solvents [285, 290]. This again suggests that speeifie solvation of the anions is responsible for the reversed order obtained in protie solvents relative to dipolar non-HBD solvents. Whereas the relative nueleophilieities in aeetonitrile are similar to those found in the gas phase [282, 285, 290], the absolute gas-phase rates are some orders of magnitude greater than those in aeetonitrile. The speeifie rates of displacement reactions of anions with halomethanes exceed those in solution by factors of up to >10 [285, 290]. These large differences in absolute rates demonstrate the moderating influence of the solvent on all the reactivities [282]. See also Chapter 5.2. 

Solvent effects on chemoselectivity. Use of donor solvents (THF or HMPT) enhances the rate of displacement reactions of lithium organocuprates with alkyl halides, but retards conjugate addition to enones. House and Lee have examined the effect of solvents on the reaction of (CH3)2CuLi with the bromo enone 1. Reaction of 1 with the cuprate in ether-(CH3)2S gives the product of... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ , ]

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